A connection was successfully established with the server, but then an error occurred during the pre-login handshake.

You know Microsoft has recently released the CTP6 or the February CTP of MS SQL Server 2008. I have downloaded MS SQL2008 CTP 6 and installed two Microsoft SQL Server 2008 February CTP instances on two different servers.

While trying to connect from one database instance to the other SQL Server 2008 database instance using the Microsoft SQL Server Management Studio, I got the following error message :

Connect to Server
Cannot connect to KatmaiCTP6.
A connection was successfully established with the server, but then an error occurred during the pre-login handshake. When connecting to SQL Server 2005, this failure may be caused by the fact that under the default settings SQL Server does not allow remote connections. (provider: Named Pipes Provider, error: 0 - No process is on the other end of the pipe.) (Microsoft SQL Server, Error: 233)

Although the error message is saying about "When connecting to SQL Server 2005", I got this message while connecting to a MS SQL Server 2008 instance.

I could solve this problem by using the SQL Server Configuration Manager. I opened the SQL Server Configuration Manager for the local database instance on the remote server. I drilled through the SQL Server Network Configuration and enabled TCP/IP protocol among the Protocols for MSSQLSERVER. TCP/IP is disabled by default so you may require to enable TCP/IP protocol for each of the SQL2008 database instances you install in order to make the database server available for remote connections using the TCP/IP protocol.